Day 20 of 30
Physical changes
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Learning Objective
Students will be able to explore physical changes.
In this lesson, we'll explore physical changes. Scientific inquiry allows us to investigate and explain natural phenomena.
Chemical reactions involve the rearrangement of atoms to form new substances with different properties. Signs of a chemical reaction: color change, gas production, precipitate formation, energy change (heat or light released or absorbed). The Law of Conservation of Mass means atoms are neither created nor destroyed—equations must be balanced. Types of reactions: synthesis (A + B → AB), decomposition (AB → A + B), single replacement (A + BC → AC + B), double replacement (AB + CD → AD + CB), combustion (fuel + O₂ → CO₂ + H₂O + energy). Acids release H⁺ ions in water (sour taste, pH < 7); bases release OH⁻ ions (slippery feel, pH > 7). pH scale: 0–6 (acid), 7 (neutral), 8–14 (basic). Reaction rates are affected by temperature, concentration, surface area, and catalysts (substances that speed reactions without being consumed).
As you work through today's material, pay attention to the examples and try to identify the patterns or strategies being used. This will help you apply these concepts to new problems.
Take notes on key points and make connections to what you've already learned in previous lessons.
To examine systematically through observation and experiment
Observable facts that support or refute a claim
Instructions
Materials Needed
- Lab notebook
- Investigation materials
- Safety equipment if needed
Based on today's lesson, what is one thing you observed or learned?
How could you test or investigate this topic further?
Why is this topic important in the real world?
Teaching Tip
For this age group: Balance direct instruction with collaborative activities. Allow students to explain their thinking and make connections to prior knowledge when exploring physical changes.